In conventional motor vehicles with internal combustion engines, a fuel pump is provided to pump fuel that is transferred from a storage tank to an internal combustion engine. Many types of fuel pumps are known, and one common type of pump uses a brushless DC (BLDC) motor drive to effect rotation of a rotor and drive the associated pump. In these fuel pumps, a power supply is connected to the motor assembly, wherein the motor assembly may include a circuit board assembled within the pump to control rotation of the rotor and drive the pump. In some BLDC motor designs, sensors may be provided to control operation of the BLDC motor. In other designs, the motor may be designed to operate without sensors by detecting operating performance of the BLDC through the control circuit operating the motor.
In conventional fuel pump systems, the pump is designed to operate at a fixed output that supports the maximum fuel flow demand of the engine. At all other times of less than maximum demand, the pump continues to operate at the same output level with excess fuel recirculated against a pressure relief valve back to the tank. The present invention enables the fuel pump output to be regulated to match the engine demand for fuel. Reducing pump output (speed) reduces electrical load on the vehicle charging system as well as reducing noise generated by the pump. The exemplary case is at engine idle condition, when fuel demand, ambient sound, and vehicle charging system output are all at the lowest due to low engine speed. In this condition, it is advantageous to slow the pump output (speed) to reduce load on the vehicle charging system electrical load and to minimize noise generation.
Therefore, it is an object of the invention to provide a variable output fuel pump, such as a sensorless BLDC fuel pump, having an improved motor assembly and an improved motor control module to allow the BLDC motor to operate through communication with a vehicle communications network such the main CANbus to provide a variable fuel supply to an engine that is regulated based upon engine requirements such as fuel flow or pressure.
In this regard, the invention relates to a fuel pump like those used in vehicular applications for pumping of fuel to an internal combustion engine, wherein the output of the inventive fuel pump is controlled or regulated by the engine control unit (ECU) or other computer control module depending upon engine requirements such as fuel pressure or flow. While the invention relates to an improved fuel pump, the invention is not so limited, wherein the improvements relate to advancements made to the motor control module that controls operation of a sensorless BLDC motor drive unit that connects to a vehicle communication network, such as a CANbus, to allow control through an engine control unit (ECU) disposed remote from the motor unit. The invention also relates to the BLDC motor control module which may have other applications in addition to use in a fuel pump or any other pump assembly.
Generally, the motor control module is used to control rotation of a rotor within the motor stator. The motor control module includes various electronic circuitry and controlling devices integrated into a circuit board that is mounted within the BLDC motor. The BLDC motor preferably is a sensorless BLDC motor which is operated based upon performance characteristics of the motor such as back emf, although the motor may include sensors such as Hall effect sensors to permit operation by the control module based upon the performance characteristics detected by the sensors. In either case, the motor control module selectively energizes the motor windings based upon the performance characteristics, and when energized, the stator creates varying electro-magnetic fields that interact with rotor magnets and thereby drives the rotor.
In the present invention, an inventive motor control module is connected to the BLDC motor to supply three power phases A, B and C to the motor. The control module is electrically connected to a main connector, wherein the main connector comprises a power supply connection that connects to a power supply such as that supplied by the battery or other power supply of a vehicle, and further comprises a vehicle network connection such as a CANbus connection that connects to a main vehicle communications network such as a vehicle CANbus or the CAN network of the vehicle. It will be understood that the vehicle communications network and ECU may use other communications protocols such as LIN or PWM besides the CANbus protocol. The motor control module interacts with these power supply and vehicle network connections to control operation of the BLDC motor.
In more detail, the power supply connects to a switch configuration that receives the main power supply and then defines three power supply lines which essentially define three power phases A, B and C supplied to the motor. The switch configuration operatively communicates with and is controlled by a motor driver such that motor operation is controlled based upon the motor performance characteristics preferably monitored or detected without relying upon separate sensors in the motor. However, it will be understood that the switch configuration also may drive a BLDC motor having motor sensors provided therein, such as Hall effect sensors which supply signals associated with the motor performance characteristics, such that motor operation is controlled by the motor driver based upon the performance characteristics detected or monitored by the motor sensors.
Generally, the motor driver is connected to a micro-controller and in turn, the micro-controller is connected to a vehicle network I/F module such as a CANbus I/F module. In this manner, the micro-controller can be operated by the vehicle control system preferably through a connection between the CANbus I/F module and the vehicle CANbus or any other suitable vehicle communication network which may use a different communications protocol as referenced above. In the illustrated embodiment, the CANbus module preferably is a CANbus transceiver that connects to a CANbus connector circuit, wherein the vehicle ECU and CANbus control operation of the micro-controller. The micro-controller may provide a motor control signal to the motor driver, wherein the motor driver operates based upon such motor control signal and thereby sequentially controls the power switches to control operation of the three power phases A, B and C to generate a variable motor speed which governs the resultant fuel pump output. Due to the variable motor speed, the pump output is also variable. As such, the variable output of the fuel pump is controlled by the engine control unit or ECU that is connected to the motor control module through the vehicle communications network so that the pump output is regulated based upon engine requirements.
In the illustrated embodiment, the motor driver also detects the performance characteristics of the power used in the three power phases of the motor so that the system preferably is operated without motor sensors located within the motor. For example, the motor driver can detect and monitor the back emf of the motor to thereby determine the motor speed. The motor performance characteristic, such as speed, can then be used to generate a feedback control signal that is communicated to the micro-controller which may then be used to modify and adjust the motor control signal. Further, the vehicle network I/F module can allow a stop signal to be communicated to the micro-controller. If desired, the direction of motor rotation can also be reversed. Still further, the micro-controller can communicate or transmit diagnostic information through the vehicle communications network to the engine control unit (ECU) or similar vehicle computer for further processing.
By connection to the vehicle communications network and ECU, this system allows the vehicle ECU to remotely control the fuel pump speed and output in response to fuel flow or pressure commands governing engine operation. If desired, service personnel can also adjust the pump operation such by remote adjustment of the speed, pump direction, and turn the pump on or off for maintenance.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.